Tuning the Polarity of MoTe2 FETs by Varying the Channel Thickness for Gas-Sensing Applications.

Asha Rani,Makarand Paranjape,Mona E Zaghloul,Md Ashfaque Hossain Khan,Kyle Dicamillo

doi:10.3390/s19112551

Abstract

In this study, electrical characteristics of MoTe2 field-effect transistors (FETs) are investigated as a function of channel thickness. The conductivity type in FETs, fabricated from exfoliated MoTe2 crystals, switched from p-type to ambipolar to n-type conduction with increasing MoTe2 channel thickness from 10.6 nm to 56.7 nm. This change in flake-thickness-dependent conducting behavior of MoTe2 FETs can be attributed to modulation of the Schottky barrier height and related bandgap alignment. Change in polarity as a function of channel thickness variation is also used for ammonia (NH3) sensing, which confirms the p- and n-type behavior of MoTe2 devices.

Highlights

Since the discovery of graphene in 2004 [1], the two-dimensional (2D) layered materials have attracted significant attention for device applications owing to their unique physical properties and promising applications in nanoelectronic devices and circuits [1,2,3,4,5]
This verifies the 2H-phase of MoTe2 and good crystalline quality used in field-effect transistors (FETs)
FETs were fabricated from mechanically exfoliated flake from chemical vapor transport (CVT)-grown single-crystal 2H-MoTe2

Summary

Introduction

Since the discovery of graphene in 2004 [1], the two-dimensional (2D) layered materials have attracted significant attention for device applications owing to their unique physical properties and promising applications in nanoelectronic devices and circuits [1,2,3,4,5]. Due to lack of bandgap structure, graphene-based transistors are difficult to switch off, which is critical for electronic devices [6]. This limitation in graphene led researchers towards layered semiconductor transition metal dichalcogenides (TMDs), which are seen as promising candidates for next-generation transistors due to their large variety of bandgap values [7,8], high charge-carrier mobility [9,10], and high on/off current ratio (~106 ) [11]. Among all TMDCs, MoTe2 is the only material which can be grown in two phases: semiconducting (2H-phase) and metallic (1T’-phase).

Methods

Results

Conclusion